From: "Shot (Piotr Szotkowski)" <shot@...>
Date: 2008-02-21T19:01:40+09:00
Subject: Re: Object#freeze as a basis for caching of method results?

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Robert Klemme:

> An alternative approach would be to use current state as cache key,
> i.e. create an immutable copy and stuff that along with calculation
> results into a Hash.

What would you say about the following approach? I=E2=80=99m not sure it sc=
ales
well, but seems to work properly, have the smallest diff impact on the
existing codebase and take object state into account=E2=80=A6



shot@devielle:~/work/PhD/bzr/trunk$ bzr diff
=3D=3D=3D modified file 'trunk/lib/art-decomp/fsm.rb'
--- trunk/lib/art-decomp/fsm.rb 2008-02-17 21:36:39 +0000
+++ trunk/lib/art-decomp/fsm.rb 2008-02-21 09:03:53 +0000
@@ -1,5 +1,7 @@
 class ArtDecomp::FSM < ArtDecomp::TruthTable
=20
+  @@cache =3D Hash.new { |hash, key| hash[key] =3D {} }
+
   attr_accessor :q, :qp
=20
   def self.from_kiss string
@@ -31,7 +33,7 @@
   end
=20
   def beta_f
-    outputs.to_blanket
+    @@cache[Marshal.dump self][:beta_f] ||=3D outputs.to_blanket
   end
=20
   def beta_q




-- Shot
--=20
So the Ether Bunny goes hippety hopity down the garden path, waylaying
innocent fieldmice and anesthetising them, so he can sell their teeth
to the Tooth Fairy to support his milk-and-cookies habit.

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